1. Field of the Invention
The present invention relates generally to an apparatus for geothermal wells. More specifically, the present invention relates to a method and apparatus for providing weight and rigidity to the piping used in vertical wells drilled for ground-source heat pumps. The invention is used to aid in inserting the piping, along with a tremie pipe, into the well.
2. Background Art
Heat pumps typically exchange heat between an indoor space and the ambient. The coefficient of performance for both the heat pump cycle as well as the refrigeration cycle is usually significantly enhanced by using ground water for the ambient because the temperature of the ground water is fairly constant at temperatures often closer to the desired indoor space temperature than the outdoor air.
To make adequate contact with the ground water, vertical wells 200 to 300 feet deep are drilled into the ground in the neighborhood of the indoor space being heated and/or cooled.
A loop of piping made of a polymer such as SDR 11 virgin polyethylene resin is inserted into the drilled well. Two pipes are involved with an elbow connecting the two at their lowest extremity in the well. The well will be completely or partially filled with water, clay, mud, sand, etc., any of which impede the insertion of the piping loop. Besides the possibility of frictional resistance to insertion, the plastic, having a density less than water, is buoyant—even when filled with water. To overcome the frictional as well the buoyancy forces, additional weight must be included with the piping. Present practice includes the use of concrete reinforcing rod and junkyard scrap iron to increase the weight of the piping for insertion. None of these materials are approved by the appropriate state organizations such as the Department of Natural Resources (DNR), or equivalent, or the appropriate federal organizations such as the National Sanitation Federation (NSF) and the Environmental Protection Agency (EPA) for contact with ground water.
The piping products used in these geothermal installations are delivered in a roll. Because the piping material has “memory,” it will retain some curvature during the insertion process, impeding the movement of the pipe into the well.
There is a need, therefore, for a system for adding weighting materials approved by the appropriate organizations (e.g. DNR, NSF, EPA, or equivalent) to the piping loops inserted into a geothermal well for a ground-source heat pump. There is additional need for a system for straightening and maintaining the straightness of the piping during the insertion of the piping into the well.